150 RAPID POPULATION GROWTH-I1
rearing the child. (The nonpecuniary attributes of some of these costs, such as the pain of childbirth, are obvious.) Second, there are the additional resource costs of rearing the child-tangible and, as a rule, pecuniary in nature. These distinctions may appear formal, arbitrary, and unhelpful to some, but they underscore the essential dual function of a child to his parents.* The psychic determinants of both demand and supply are rooted in nonpecuniary values that resist tangible measurement, and are revealed only indirectly by means of micro-analysis, if at all. The second category of determinants is more likely to take a pecuniary form, submit to ordering, and admit to micro-analysis.
Nonpecuniary Returns from Children
We know little about the factors that lead different parents to make different appraisals of the intangible returns from children. On this point, consumer behavior theory is quite empty (6, 7). Economists commonly assume that differences among individuals in appreciating various consumer goods or activities is a function of their particular preferences. In other words, in an economic system people differ in their tastes, and implicitly tastes are taken as primitive or axiomatic to the system. Explicitly, these preferences are treated at a combination of specific tastes, each independently distributed across populations. However, consumer behavior theory provides one relevant implication—that an individual's satisfaction from any particular consumption activity tends to be subject to diminishing returns as that activity is engaged in more extensively. Satisfactions from additional children may diminish with increasing family size or number of surviving offspring/'
It is important to probe beneath basic preferences in order to deal with the factors that mould an individual's preferences.* What measurable, variable, and possibly manipulatable elements of an individual, his culture, or his consumption activities determine his preferences for specific activities? Determinants or tastes may be more properly the domain of the sociologist, psychologist, and anthropologist; and a review of their literatures is not intended here. Nevertheless, however conceptualized and quantified, assessing
*As discussed in the ncxt-to-last section, the neglect of intangible returns from children pervades the economic literature on population policy and optimum population criteria. On the other hand, some critics from sociology misinterpret the generality of the economic framework properly stated (5), and ignore its compatibility with their viewpoint.
1'The extreme case can be documented by casual empiricism. I-'or example, Wray (in this volume) reports evidence that the larger the number of children, the greater the jeopardy to the health of the parents and to the physical and mental development of children. If this association is a causal relationship and parents perceive the relationship, then one might argue the nonpecuniary returns to additional children had become strongly negative.
•I'ln the economic literature occasional efforts have been made to express eonsuwp-